DISSERTATION RESEARCH: Islands on Islands on Islands: Bacterial Metacommunity Evolution in a Prairie Dog Landscape

跳蚤可以将疾病的细菌从一种动物带到另一种动物，也可以从野生动物带到人类。跳蚤是否能够成为病原体的合格媒介取决于许多不同的因素。这一过程中被忽视的一个方面是生活在跳蚤肠道内的细菌群落的动态。跳蚤携带的不是单一种类的细菌，而是整个群落，细菌群落的组成和组装可能会影响跳蚤是否是有能力的媒介。该项目旨在评估空间、时间和种间相互作用对感染草原土拨鼠的跳蚤内细菌群落聚集的影响。跳蚤是在2004年和2007年从生活在不同群体中的动物身上收集的。从数百只跳蚤中提取了DNA，并将使用焦化测序法从跳蚤DNA样本中产生数十万个细菌DNA序列。这些细菌DNA序列将被用来确定在某个草原犬类群体(空间)内，在某个年份(时间)内，细菌群落是否更相似，以及细菌谱系之间的相互作用是否控制着群落组装。此外，还将利用系统发育技术将细菌群落聚集与跳蚤和草原狗的种群结构联系起来。这项工作将推进对疾病媒介内细菌群落动态的研究，并将重点关注一个研究较少但潜在重要的问题：即媒介内细菌群落的组成是否存在显著差异，以及这种差异是否可以解释媒介能力的差异。此外，随着对作为个体的微生物生态系统的描述和理解的日益重视，这项工作将会更加深入。

Fleas can carry bacterial agents of disease from one animal to another, and from wild animals to humans. Whether a flea is capable of being a competent vector for pathogens depends on a number of different factors. An overlooked aspect of this process is the dynamics of bacterial communities that live within the gut of fleas. Fleas do not carry a single species of bacteria, but an entire community, and the composition and assembly of the bacterial community may influence whether fleas are capable vectors. This project seeks to assess the effects of space, time, and inter-specific interactions on bacterial community assembly within fleas that infect prairie dogs. Fleas were collected in 2004 and 2007 from animals living in discrete colonies. DNA was extracted from hundreds of fleas, and pyro-sequencing will be used to generate hundreds of thousands of bacterial DNA sequences from the flea DNA samples. These bacterial DNA sequences will be used to determine if bacterial communities are more similar within a certain prairie dog colony (space), within a certain year (time), and if interactions between bacterial lineages govern community assembly. In addition, phylogenetic techniques will be used to relate bacterial community assembly to flea and prairie dog population structure. This work will advance studies of the dynamics of bacterial communities within disease vectors, and will focus attention on a little studied but potentially important issue: namely, whether the composition of bacterial communities within vectors varies significantly and if such variation can explain variation in vector competency. Furthermore, this work will dove-tail with the increasing emphasis on describing and understanding the microbial ecosystem that is an individual.